In field use, such as in an electric generating plant, it is desired that numerous telephone handset stations communicate with one another. Such systems typically employ a page line and a party line for station to station communications. Many older systems employ audio techniques for such communications which give rise to various problems. These problems include excessive noise, signal fade and general lack of clarity of the voice after signal transmission plus overcrowding. A major limitation of such prior systems is their inability to handle more than one conversation at a time.
A particular aim of the present invention is to provide an improved and expanded telephone communication system for a field installation which utilizes existing field wiring and enclosures.